oil change question

[soslow]

A few days ago I brought my 1990 ZR-1 in for an oil change and specified to the mechanic that I wanted Mobil 1 High Mileage oil. He replaced the 8.5 quarts and gave me a half quart to bring home. When I got home, I noticed that he put in 5w-30 weight oil instead of the 10W-30 that the car calls for. Is this a big deal? It is synthetic and has some 10W-30 from the last oil remaining that doesn't drain out. Any thoughts?
The car only has 11,000 miles on it.

[Dynomite]

In New York it is getting cold so lighter oil is better this time of year.

[George Maz]

In New York it is getting cold so lighter oil is better this time of year.

Yes, I agree. It's 65°F day and 45°F nighttime.
I just drove around for two hours and my temps are much lower than summertime...coolant 75-85°C
I use Amsoil 10w-40 and Mobil1 15w-50 in each car, they are ready for oil changes soon.

[WVZR-1]

I don't know that it's that easy to just let the facility "off the hook" - I've no "first hand" but I'd think there's little argument for the change from 10/30 product to the 5/30 product for a car that isn't going to see "everyday" use. Even then I'd maybe think very hard before the change.

Maybe you make the facility aware of what was done and negotiate a change to the 10/30 in the spring. A '90 MY with 11K should certainly still have the OE oil fill cap that specifically states 10/30 and I'd have thought anyone I do business with would ask first.

I've a 3800 SSEi SC and from time to time I use a quick-serve facility for the oil change and they go out of their way to mention they've used the 10/30 spec on the oil cap. Until very recently they used bottled product but they've added 10/30 bulk and now they ask which!

[soslow]

Thanks guys, I appreciate the input; I called Vette Doctors over in Amityville and they said pretty much what you guys advise, winter is coming, and with the lighter oil, it really wouldn't hurt the engine. I did let the facility know that they put in the wrong weight oil and they couldn't care less. I was using them for all three of my cars and now they blew it.

[Roadster]

I don't know that it's that easy to just let the facility "off the hook" - I've no "first hand" but I'd think there's little argument for the change from 10/30 product to the 5/30 product for a car that isn't going to see "everyday" use. Even then I'd maybe think very hard before the change.

I agree with the above and would like to add, that even if the car was used for everyday driving and you have the 5W-30 oil in there, it is not going to do any damage or have additional wear as you may think. While I am not an oil expert, and don't pretend to be, just thinking out loud that if your not using your ZR-1 for strictly performance purposes, then you have nothing to worry about. If it is purely a track vehicle, then that is something else!!!
Our '03 Vibe now is @ 170,000 miles, and still runs strong. Use oil, yes it does, more probably leaks then burning. Add up to a 1/2 quart from time-to-time. And I just use conventional oil in that car. My point is no matter what oil you use, you can get longevity from any engine when properly maintained, which means doing PM's and having the correct fluids. That being said, if that shop put in 20W-50, or 15W-50, or straight 30 or 40W, then that would be a cause for you to be upset. JMO.......

Just another side note, way back when oils were a lot different and didn't have quite the viscosity ranges that they have today. Even on cold morning with a slightly heavier "weight" oil, sure it may have taken a few extra seconds to start the engine on a cold morning, but you just let the engine warm up a little bit longer, of course today, it's totally different. You would have to completely abuse your engine in some way, shape, or form, to verify that the difference between a 5W & 10W oil for cold weather starts is damaging your engine in colder climates.....

[soslow]

I think that I am more concerned with the issue that the owners manual clearly states "For the LT5 engine use only 10w-30 weight oil" an it is also printed on the oil filler cap and I specifically told the shop to use it. But, alas, they used 5w-30 instead and didn't tell me. I didn't want to be neurotic about it, as the experts at Vette Doctors said it would be OK, but I had to be forced to do the research after the fact to put my mind at ease after the deed was done. Reading that specific sentence in the manual made me concerned, I felt for good reason as I am not a mechanic.


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[Roadster]

I think that I am more concerned with the issue that the owners manual clearly states "For the LT5 engine use only 10w-30 weight oil" an it is also printed on the oil filler cap and I specifically told the shop to use it. But, alas, they used 5w-30 instead and didn't tell me. I didn't want to be neurotic about it, as the experts at Vette Doctors said it would be OK, but I had to be forced to do the research after the fact to put my mind at ease after the deed was done. Reading that specific sentence in the manual made me concerned, I felt for good reason as I am not a mechanic.


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Yes, I understand your concern, and rightfully so.....but also understand that oil technology has jumped leaps and bounds since the 90's and before.....I do not have my owners manual in front of me, but sometimes, (not saying the ZR-1 manual does), the oil recommendation will cover a more slightly given range according to your climate conditions where you live.
I now use Mobil 1 10W-40 High Mileage in mine. Went on recommendations of the ZR-1 experts here on the forum, which there are quite a few....:-D
I am not concerned about cold weather starting at all. Mine is garaged, and regardless of what time of year it is, when I start the Z, I back out and let it warm up so that the coolant reaches 200 degrees and above. In doing that the oil temp also gets near the correct operating temps that it should be for wide open throttle operation if need be.....this way I avoid jumping on the highway and maybe using more throttle than necessary on a cold engine to get into the flow of traffic. Overkill.....probably, but that's what I do. You will do more damage to your engine using more throttle (then need be) when cold and not fully at operating temps, than being concerned about your oil weight (viscosity)difference between a 5W & 10W oil.
Do not take this the wrong way, you did the right thing in asking questions and doing your research. At my age I still do research :) and constantly learn each day. And again, these are JMO's, from my experience of car ownership of some very high mileage motors throughout my years.
Enjoy your Z, always check your fluids, tighten up all of the "screw" connections on the engine every so often, (vibration=loose screws) which can turn into annoying leaks..(of different kinds). Get into the habit of doing PM's (Preventative Maintenance) on a periodic basis, and you will have many enjoyable years of ownership.....:cheers:

[Paul Workman]

Hard to think of another topic hashed more and seeded with as much sales hype and in some cases misinformation as oil. Chemical engineering ain't my long suit: I have lots of company I'm sure.

So! What's the best answer? Are bought and paid for studies honest? What lubrication requirements are unique specifically to the LT5 that might frame the decision/choices?

Far beit from me to presume ro offer expert opinion or recommendations based personal expertise. But, it is possible, I think, to identify some of the most important things which distinguish the motor from some of those others with their pushrods and roller tappets, and limited rpm range, for example,

The things that jump out at me and other students of the LT5's characteristics is: flat tappets, 7000+ rpm redline, long and numerous chains, smallish cam sprockets, viscosity srability of synthetic oils over extreme temperature change, the chemical makeup (features) of oils specifications at the time the motor was built.

All this considered as well as recommendations from those knowledgeable people I and others trust, is how I came to settle on Amsoil 10W-40 recommended by Marc Haibeck.

I'm more WARRIOR than WAXER. 7000+ rpm reached ea. outing is "normal". In it's 9th season now, and she runs like a fine watch. So far so good! I'll stick with what is working in the knowledge unique LT5 requirements are specifically being met...at least so it seems!

[soslow]

I greatly respect your experienced opinion and the expertise of Marc Haibeck so I think you guys have me convinced. I'll consider my Mobil1 High Mileage 5w-30 oil change an engine flush for the winter, where I don't use the Z much anyway and in the spring I will follow your recommendation with the Amsoil 10w-40 from then on. Thanks.


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[Hog]

A few days ago I brought my 1990 ZR-1 in for an oil change and specified to the mechanic that I wanted Mobil 1 High Mileage oil. He replaced the 8.5 quarts and gave me a half quart to bring home. When I got home, I noticed that he put in 5w-30 weight oil instead of the 10W-30 that the car calls for. Is this a big deal? It is synthetic and has some 10W-30 from the last oil remaining that doesn't drain out. Any thoughts?
The car only has 11,000 miles on it.The 5W30 will have the exact same viscosity at 100ºC/212ºF as the 10W30 oil will. The difference will be during cold start temperatures, where the 5W30 oil will flow easier than the 10W30 will. Your engine may in fact have a decrease in cold start wear as the 5W oil will flow easier at that lower cold start temperature.
Since it sounds as though you have the luxury of being able to drive your Z in the Winter(I envy you) simply start up the Beast and drive it. IMO No need to warm up an EFI car, nothing gets you engine up to operating temperature faster than gently driving it. Having it sit there and idle merely prolongs the amount of time that elapses before your engine reaches operating temperatures. Very little wear occurs during normal driving, most of it occurs during cold starts.

OEMs have been decreasing the cold temperature viscosity numbers over the years. In the 90's it was 10W, then went down to a thinner 5W**, and now is down to a 0W for many OEMs.

IMO In regards to the LT5. I feel that its more important to provide an engine oil that has the proper high pressure lubricants package for the lobe followers/lifter, chains and the large chain guide surface area(as well as other areas)as there are not a roller type, than worry about the cold(Winter) viscosity number of an engine oil, esp. a synthetic oil. The synthetic oils that some people use have much better cold flow properties than conventional oils do.
And at the other end of the spectrum temperature wise, synthetics are superior in terms of high thermal stability. This would be of great concern IMO in an early car with OEM turbocharging such as the Callaway Corvettes rpo B2K. Though they didn't use flat tappets, they did have rocker arms that exhibit galling above 6000rpm(not an issue in OEM parameters).

Of course all of my opines here excuse non of the issues that you should have with the oil change business that provided you with an incorrect fill.

[Hib Halverson]

For 1990-1992, the factory fill oil for an LT5 engine was a 10W30 petroleum-based oil (not synthetic) and Mobil Oil was the supplier.

For 1993-1995 the factory fill in an LT5 was a 5W30 synthetic "Mobil 1".

A 5W30 synthetic can be used in the early engine with no ill effects.

In fact, you don't even need M1 "High Milage" because the LT5, by virtue of its OHC valve train, doesn't require additional ZDDP.

If I still owned my ZR-1 what would I put in it? Gibbs Driven LS30 which is a 5W30 with a more advanced base stock than any of the Mobil 1 products use.

For frequent track use, I'd go with Gibbs Driven DT40 a 5W40 which uses the same mPAO base stock.

[Paul Workman]

Thanks, Hib for "turning the page". The "m" in "mPAO" is a proprietary process developed by ExxonMobil, marketed under the "Driven" banner, ,if I'm not mistaken.

I think all would agree that testimonials are far from scientific evidence - mine included. And, too (oil) suppliers' marketing hype is also suspect - perhaps the worst, in some cases.

http://www.deluxeoil.com/royal_purple_claims.htm

It would sure be refreshing to see independent test comparisons of leading brands (beit Amsoil or whatever) that are conducted in such a way as to be clearly understood by laymen. (I'd like to see how the mPAO compares to leading brands; tests done in a way the LT5 - in particular - could be demonstrated. (Considerations for timing chain lengths, cam sprocket loading, rpm, etc.)

And, too... There's "the BEST" and then there's "GOOD ENOUGH" to be considered. I haven't seen a test that is specific to the LT5's unique criteria to make a "good enough" determination. But, regardless of what I or any of us is aware of, is not exceeding the "good enough" product with one providing an extra margin for error a good thing - especially considering the cost to repair the LT5?

Looking forward to the next independent, comprehensive analysis including the "Driven" products alongside of other top brands.

[Dynomite]

Most guys reading all this now do not know what to do :D

You guys make it soooooo complicated. I shall make it simple ;)

http://i287.photobucket.com/albums/ll142/dynomite007/Dynomite6/353a8770-2463-4a3d-bd53-860920b2b618.jpg

[Paul Workman]

Most guys reading all this now do not know what to do :D

You guys make it soooooo complicated. I shall make it simple ;)

http://i287.photobucket.com/albums/ll142/dynomite007/Dynomite6/353a8770-2463-4a3d-bd53-860920b2b618.jpg

Ockham's razor...;)

[scottskill]

I would recommend AMSOIL Z-ROD 10W-30.

[Hog]

For 1990-1992, the factory fill oil for an LT5 engine was a 10W30 petroleum-based oil (not synthetic) and Mobil Oil was the supplier.

For 1993-1995 the factory fill in an LT5 was a 5W30 synthetic "Mobil 1".

A 5W30 synthetic can be used in the early engine with no ill effects.

In fact, you don't even need M1 "High Milage" because the LT5, by virtue of its OHC valve train, doesn't require additional ZDDP.

If I still owned my ZR-1 what would I put in it? Gibbs Driven LS30 which is a 5W30 with a more advanced base stock than any of the Mobil 1 products use.

For frequent track use, I'd go with Gibbs Driven DT40 a 5W40 which uses the same mPAO base stock.


You make a great point about the DOHC architecture. Seeing that it doesn't use the "cam lobe/lifter force multipliers" aka in a 1.5:1 ratio that most GEN 1 and GEN 2 pushrod SBC's used (except 96-97 LT4 which used the 1.6:1 ratio) less force exerted by the LT5 OEM valvesprings don't require the pressures that the pushrod engines did.

On average though, most oils have in fact reduced the amount of ZDDP contained within since the GEN 1 and GEN 2 LT5's were designed built (all done by MY1993).
The entire Mobil One lineup ranges from 800ppm for the Extended line, around a 1000-1300 for most of the rest of the M1 line(depending on viscosity. With their race only Mobil 1 Racing with 1850ppm.

Extra Zinc depends upon the oil referenced, formulations from the early 90's are different than 2016.

I would love to see a 100,000mile 1992 engine run on its OEM conventional spec oil and a 1993 GEN2 LT5 its OEM synthetic spec oil with 100,000miles on it, both disassembled and compared.

Question: Would the area between the flat tappet and cam lobe, be the area of highest of contact pressure inside the LT5?
I know that the Zinc in oils is useful as a high pressure lubricant.
As always, thanks for your input Hib.

And yes, the other Paul, I agree that testimonials are far from scientific, no matter who is giving them.

Edit: Here are the Mobil 1 specs (current as of Feb 2016) that I was roughly referencing.
https://mobiloil.com/~/media/amer/us/pvl/files/pdfs/mobil-1-oil-product-specs-guide-2016.pdf